Industrial water systems typically contain charged contaminants that are prone to precipitation from water as well as accumulation on industrial equipment surfaces. Common water contaminants such as calcium, iron, magnesium, barium, and aluminum, when present in feed water, are the major cause of scaling and corrosion in industrial water systems. Scaling and corrosion of system components can cause heat exchange inefficiency, fluid flow impedance, and bursting of pipes, potentially resulting in process shut-downs and production time loss. The time and financial loss associated with scaling and corrosion has resulted in the use of chemical treatments to reduce the presence of problematic metal contaminants in industrial water systems.
Chemical treatments are commonly used to control, reduce, and sometimes prevent the development of scale and corrosion. Chemical scale inhibitors act by interfering with crystallization, attachment, and/or deposit consolidation of water contaminants. In particular, anionically charged polymers (i.e., anionic polymers) can act as anti-scaling agents by removing dissolved and particulate cationic metals from water. The effectiveness of the anionic polymer is optimal when the polymer is maintained at an acceptable level. If the level of anionic polymer is too low, the amount of scaling and corrosion will increase. However, employment of an excess amount of anionic polymer results in unnecessary costs. Thus, the polymer treatment must be carefully monitored and controlled using accurate methods.
Spectroscopic methods in combination with indicator dyes can be used to detect and monitor the concentration of anionic polymer treatments in industrial water. When anionic polymers are exposed to an indicator dye capable of associating with the polymer, a complex results which can undergo spectroscopic analysis using ultraviolet, visible, or infrared light to ascertain the amount of polymer in the water system.
While many existing indicator dyes are useful in monitoring anionic polymer concentration, some suffer from disadvantages including high sensitivity to testing conditions and instability in aqueous solutions. Thus, many indicator dyes fail to provide consistent and reproducible results.